1. Field of the Invention
The present invention relates to an aspirator to be used for ophthalmic surgery of the vitreous body and a cataract.
2. The Related Prior Art
(1) An aspirator for ophthalmic surgery removes a translucent portion of the vitreous body in the eyeball by suction. The aspirator may include, for example, one bottle. The bottle is provided with two passages. One of the passages is connected to a vacuum pump and the other communicates with the open air. Control of opening or closing the two passages by the vacuum pump can adjust the pressure in the bottle and the translucent portion of the vitreous body is sucked into the bottle by means of vacuum in the bottle.
It is to be noted, however, that control apparatus becomes complicated when control over the opening o closing of the two passages is be required.
(2) An aspirator (M) for surgery is provided with two bottles, larger and smaller, and the two bottles are connected to each other through a pipe. The pipe is further provided at its intermediate portion with a branch pipe which, in turn, is connected to a surgical apparatus and which is further provided with a valve for controlling the flow rate of materials to be aspirated and sucked through the pipe.
Another aspirator (N) for ophthalmic surgery is provided with one bottle which, in turn, is fitted with a conduit for supplying vacuum and with a conduit for communicating the pressure in the bottle with ambient air. A valve is mounted on each of the conduits and the pressure in the bottle is adjusted to a predetermined pressure by controlling each of the valves.
It is to be noted, however, that the former aspirator (M) must interrupt aspiration of materials to be aspirated and sucked during the period of time when the aspirated materials stored in the smaller bottle are to be transferred to the larger bottle. This leads to frequent interruptions in the surgery.
For the latter aspirator (N), only one bottle is used so that the time required to each the predetermined pressure necessary for aspiration varies with the quantity of the sucked materials stored in the bottle. For instance, when a bottle is large in volume and empty, the time required for aspiration becomes too long.
(3) Furthermore, conveyance of the sucked materials through a flexible passage portion in an aspirating cassette, when the aspirator having a materials-passage opening/closing unit of this type is suspended, by pressing a portion of the materials-passage opening/closing unit in the aspirator onto the flexible passage portion in response to a signal. Conveyance of the aspirated materials through the passage portions is resumed by returning the portion of the materials-passage opening/closing unit to its original by discontinuing the pressing onto the passage portion.
It is, however, to be noted that the above-mentioned aspirator is such that the force for squeezing the passage portion by means of the portion of the materials-passage opening/closing unit is also applied to the aspirating cassette when conveying the aspirated materials through the flexible passage portion, in other words, upon or during pressing the portion of the materials-passage opening/closing unit onto the aspirating cassette.
In this case, the aspirating cassette may be inclined by the force applied, thus breaking the connection of an accommodating unit in the aspirating cassette with a vacuum controlling unit in the main body of the aspirator itself or causing the aspirating cassette to come off from the main body of the aspirator. This may incur the risk of interfering with the surgery and endangers the safety of the surgery.